Monitoring apparatus for detecting the passage of objects past a point

ABSTRACT

Apparatus for use with coded-vehicle identification systems for detecting the passage of the ends of railroad cars past a detection point. The apparatus determines the time interval between passage of adjacent wheels of each truck of a car past the detection point, and indicates that a truck has completely passed the detection point when a period of time equal to 1.6 times the time interval between passage of the last two wheels has elapsed without detection of another wheel. An end-of-car signal is produced at a time after the last wheel of the second truck has passed the detection point equal to 1.6 times the timer interval between passage of the last two wheels of the second truck. For the majority of railroad cars of the flat car type used in &#39;&#39;&#39;&#39;piggyback&#39;&#39;&#39;&#39; operations this end-of-car signal occurs as the region of the coupler passes the detection point. The apparatus also provides appropriate end-of-car signals for certain less common car configurations, and also includes arrangements for maintaining the apparatus in synchronism with the cars of a train by checking the occurrence of the coded labels on the cars.

nite States Patent 1 e v [111 warm Arevian et al, [45] May 1, R973 MONITORING APPARATUS FOR Primary ExaminerMaynard R. Wilbur DETECTING THE PASSAGE ()F Assistant Examiner.loseph M. Thesz, Jr. OBJECTS PAST A POINT Attorney-Norman J. OMalley [75] Inventors: Garo Arevian, Whitman; Wilson P. 7

Boothroyd, Carlisle; Elton E. Dun- [5 1 ABSTRACT bar, Waltham, all of Mass. Apparatus for use with coded-vehicle identification systems for detecting the passage of the ends of rail- [73] Asslgnee: GTE Informatlon Systems lncorroad cars past a detection point. The apparatus deterporated mines the time interval between passage of adjacent [22] Filed: Aug. 6, 1971 wheels of each truck of a car past the detection point,

[ 1 pp 169 762 and indicates that a truck has completely passed the detection point when a period of time equal to 1.6

times the time interval between passage of the last two [52] US. Cl. ..235/92 FQ, 340/1463 K, 235/92 R, wheels has elapsed without detection of another 235/92 C, 235/92 CC, 3 0/3 R wheel. An end-of-car signal is produced at a time after [51] Int. Cl. ..B61l 1/16 the last wheel of the second truck has passed the d [58] Field of Search ..235/92 TC, 92 T, teetion point equal to 1,6 times the timer interval 235/92 92 F0, 2 C 340/1463 38 between passage of the last two wheels of the second 247 truck. For the majority of railroad cars of the flat car type used in fpiggyback operations this end-of-car References Cited signal occurs as the region of the coupler passes the detection point. The apparatus also provides ap- UNITED STATES PATENTS propriate end-of-car signals for certain less common 3,582,969 6/ 1971 Kinney ..235/92 FQ car configurations, and also includes arrangements for 3,497,633 2/1970 Jordan et film maintaining the apparatus in synchronism with the 3,486,008 12/1969 Mori ..340/l46.3 K Cars f a train by checking the Occurrence f the coded labels on the cars.

15 Claims, 9 Drawing Figures 20 i LABEL SIGNAL DECODING SCANNING READOUT :1) PROCESSING LOGIC :11 CIRCUITRY CIRCUITRY APPARATUS VEHICLE LABEL PARITY 1 WC2 WHEEL WHL END-OF-CAR o SENSOR DETECTOR LABEL-EOC NO LABEL-EOC LR (RESET) K w K25 Pat nted May 1, 1973 8 Sheets-Sheet ,1.

L [l I! [I I J\ h l: J 13 15 10 14 13 15 1O 14 2o 21 L 22 25 LABEL f,

- SIGNAL DECODING SCANNING I READOUT PROCESS|NG: LOGIC :1) mm CIRCUITRY CIRCUITRY APPARATUS \VEHICLE LABEL PARITY1 W02 WHEEL wHL END-OF-CAR o SENSOR DETECTOR LABEL-EOC NO LABEL-E00 LR (RESET) MONITORING APPARATUS FOR DETECTING THE PASSAGE OF OBJECTS PAST A POINT BACEKGROUND OF THE INVENTION This invention relates to apparatus for monitoring the movement of objects past a point. More particularly, it is concerned with apparatus for monitoring the passage of railroad cars past a point on a pair of tracks.

A label reading system for identifying railroad cars or other vehicles has been described in US. Pat. No. 3,225,177 entitled Mark Sensing" and issued on Dec. 21, 1965, to Francis H. Stites and Raymond Alexander and in US. Pat. No. 3,417,231 entitled Mark Sensing System and issued on Dec. 17, 1968, to Francis H. Stites and Bradstreet J. Vachon. In the system as described in these patents, labels have data pertinent to the vehicles encoded therein by means of a plurality of reflective stripes and are affixed to the sides of railroad cars. As a labeled railroad car passes a trackside optical scanning unit, the coded pattern of the label is sensed and translated into electrical signals which are appropriately processed and decoded to obtain the information encoded in the label.

In such a system it is important to detect the passage of each railroad car past the scanning unit by means other than reading labels so that the passage of an unlabeled car can be indicated. Since the practice adopted as standard by the American railroads for the majority of railroad cars requires that the label be mounted in the region between the innermost wheels of the two trucks of a railroad car, a relatively simple wheel counting apparatus has been considered satisfactory. The wheel counting apparatus produces a signal indicating the passage of a car past the trackside unit on the second count of a wheel subsequent to detecting the presence of a car label. The apparatus also produces a signal on the seventh count of a wheel subsequent to detecting a car label, unless it is reset by detecting a car label after the second wheel and before the seventh wheel. Such a signal indicates the passage of an unlabeled car.

This arrangement has been found to work satisfactorily since most railroad cars have two trucks, both with either two or three axles. In addition, the arrangement is self-synchronizing; that is, the occurrence of errors does not interfere with subsequent proper operation of the system. However, the signal indicating passage of a car past the trackside unit occurs one or more wheels prior to passage of the end of a labeled car, and one or more wheels prior to or after the passage of the end of an unlabeled car. Although this situation is of no significance in reading labels on box cars, it does cause limitations in so-called piggyback operations in which-labeled trailers or containers are carried on flat cars.

A system for reading labels on flat car type carrier vehicles and on trailers or containers carried thereon in piggyback arrangement and for correctly associating the data on the trailers or containers with the data on the carrier vehicles is described in US. Pat. No. 3,553,433 entitled Data Storage and Transfer Apparatus for Plural-Vehicle Identification Systems and issued on Jan. 5, 1971, to Gordon B. Sorli. The wheel counting apparatus as described hereinabove when employed with a system such as described in the patent to Sorli provides signals indicating the passage of cars which permits proper operation of the system in associating data on trailers or containers with the appropriate carrier vehicle so long as the trailers or containers are placed on the flat-bed carrier with their labels located between the innermost wheels of the two trucks. If a trailer or container label is located outward of a truck, the signal indicating that the carrier has passed the trackside unit will occur before that label has been read, and thus the trailer or container will be incorrectly associated with the following carrier vehicle.

SUMMARY OF THE INVENTION Apparatus in accordance with the present invention provides a signal indicating passage of a railroad car approximately as the end of the car passes the trackside unit. The apparatus includes a sensing means for sensing the passage of an object, such as an axle, past a point on the path of movement of the object. A first timing means coupled to the sensing means measures the time interval between passage of adjacent objects of a group, such as adjacent axles of a truck, past the point. A second timing means coupled to the sensing means and to the first timing means provides an indication a calculated period of time after passage of the last object of the group past said point. The calculated period of time bears a predetermined relationship to the time interval between passage of the next-to-last and last objects of the group past the point.

The apparatus also includes an output means which is coupled to the second timing means and produces an output signal in response to an indication from the second timing means after passage of a second of a group of objects, such as the second truck of a car, past said point; the indication occurring subsequent to an indication from the second timing means of the passage of a first group of objects, such as the first truck of a car, past the point. Thus, the apparatus provides an output signal after a railroad car has moved a distance bearing a predetermined relationship to the spacing between the. last two axles of the second truck subsequent to the last axle of the second truck being sensed. The predetermined relationship is such that the distance is approximately the spacing from the last axle of the car to the region of the coupling, providing a substantially end-of-car detection system.

It is an additional feature of apparatus in accordance with the invention to include closely-coupled car detection means which produces a signal if the first axle of the following car is detected after passage of the last axle of the second truck of the previous car past said point but before an indication is produced by the second timing means. The signal from the closely-coupled car detection means is coupled to the output means and causes the output means to produce an output signal.

It is another feature of the apparatus in accordance the synchronizing means to the output means causes the output means to produce an output signal in response to the next indication from the second timing means occurring after passage of another truck past said point.

BRIEF DESCRIPTION OF THE DRAWINGS Additional objects, features, and advantages of apparatus in accordance with the present invention will be apparent from the following detailed discussion together with the accompanying drawings wherein:

FIG. 1 is a representation of two labeled carrier vehicles of a railroad train carrying labeled trailers in a piggyback arrangement;

FIG. 2 is a block diagram of an automatic car identification system for use in reading labels on railroad cars and piggyback trailers as the railroad cars pass a point along the tracks, the system including an end-of-car detection apparatus in accordance with the present invention;

FIG. 3 is a block diagram of the end-of-car detection apparatus of FIG. 2 illustrating the major sections of the apparatus and their interconnections;

FIG. 4 is a detailed block diagram of timing and wheel synchronizing circuitry employed in the apparatus of FIG. 3;

FIG. 5 is a timing diagram showing the relationships of the timing signals produced by the timing and wheel synchronizing circuitry of FIG. 4;

FIG. 6 is a detailed block diagram of a gap detector employed in the apparatus of FIG. 3',

FIG. 7 is a detailed block diagram of a profile detector employed in the apparatus of FIG. 3;

FIG. 8 is a detailed block diagram of EOC/reset circuitry employed in the apparatus of FIG. 3; and

FIG. 9 is a detailed block diagram of a profile synchronizer employed in the apparatus of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION General Description FIG. 1 is a pictorial representation of two fiat car type railroad vehicles 10 each carrying two trailers 11 and 12 in a piggyback arrangement. The carrier vehicles 10 are a standard type including a pair of trucks 13 and 14 positioned equidistant from the center of the car. Each truck 13 and 14 as shown has two axles, or two wheels on each side of the car. Although not illustrated, another standard type of carrier vehicles to be discussed herein employes trucks with three wheels.

The carrier vehicles 10 have labels 15 of the type described in the aforementioned patents to Stites and Alexander, and Stites and Vachon, which labels are mounted centrally of the cars. Each trailer 11 and 12 also has a label 16 and 17 mounted thereon for identifying the particular trailer. The labels affixed to the carrier vehicle 10 and to the trailers 11 and 12 are appropriately encoded in order to distinguish between the carrier vehicles and the trailers as described in the patent to Sorli.

The system for reading the labels on the carrier vehicles 10 and on the trailers 11 and 12 includes a scanning unit 20 as illustrated in FIG. 2 which is mounted adjacent the railroad tracks. The scanning unit scans a beam of light vertically upward along the sides of the vehicle to intercept the label. Light reflected from the label is converted to electrical signals by the scanning unit. The electrical signals are processed by signal processing circuitry 21 to eliminate the effects of noise and provide standardized signals to the decoding logic circuitry 22. The decoding logic circuitry 22 decodes the incoming signals and presents the decoded information in a suitable format to an appropriate readout apparatus 23.

The decoding logic circuitry 22 includes various arrangements for checking the authenticity of the received signals as valid label data signals. As described herein it also includes a parity checking arrangement of a type described in U.S. Pat. No. 3,524,163 entitled Parity-Checking Apparatus for Coded-Vehicle Identification Systems" which issued on Aug. 11, 1970, to Henry N. Weiss, or in U.S. Pat. No. 3,525,073 entitled Parity-Checking Apparatus for Coded-Vehicle Identification Systems" which issued on Aug. 18, 1970, to Gordon B. Sorli and Sergio Calderon.

A wheel sensor 24 provides a signal to an end-of-car detector 25 each time a wheel, or axle, passes a wheel detector located at a detection point along the track. The end-of-car detector 25 provides an appropriate signal to the decoding logic circuitry 22 as the region of the end of each carrier vehicle passes the wheel detector. Other wheel count data is also transmitted from the end-of-car detector 25 to the decoding logic circuitry 22. The end-of-car detector 25 receives information from the decoding logic circuitry 22 when the presence of a carrier label is detected and also when the label satisfies the parity requirement.

The wheel sensor 24 and end-of-car detector 25 are illustrated in the block diagram of FIG. 3. Timing and wheel synchronizing circuitry 30 produces a set of timing pulses for operating the other sections of the apparatus. The timing pulses are appropriately synchronized with a signal (WHL) from the wheel sensor 24 indicating the passage of a wheel past the wheel detector. A gap detector 31 employs information received from the timing and wheel synchronizing circuitry 30 to produce a signal (B FULL) when the last wheel of a truck has moved a certain distance past the wheel detector, the distance being equal to the anticipated spacing between the last wheel and the end of the car. A profile detector 32 employs signals from the gap detector 31 and from the timing and wheel synchronizing circuitry 30 to generate signals concerning the car profile (the arrangement of wheels and trucks on the car). Information from the gap detector 31 and profile detector 32 together with timing signals from the timing and wheel synchronizing circuitry 30 are employed by EOC/reset circuitry 33 to produce an end-of-car (EOC) output signal approximately as the region of the coupler at the end of the car passes the detection point. The EOC output signal is applied to the decoding logic circuitry 22. The EOC/reset circuitry 33 also receives information from the decoding logic circuitry 22 on whether or not the car is labeled, and the end-of-car signal applied to the decoding logic circuitry 22 is either a LABEL-EOC or a NO LABEL- EOC signal. A profile synchronizer 34 employs infor mation relating to the detection of a car label, the generation of an end-of-car signal, and the car profile to determine if the apparatus is properly synchronized with the car profile and to generate corrective signals to obtain proper synchronization if necessary.

Timing and Wheel Synchronizing Circuitry The timing and wheel synchronizing circuitry 30 is illustrated in detail in FIG. 4. FIG. 5 is a timing diagram of the various signals produced by the timing and wheel synchronizing circuitry 30 and employed throughout the apparatus. The timing and wheel synchronizing circuitry includes a square-wave oscillator 40 which may operate, for example, at a frequency of 160 kilohertz. The output of the square-wave oscillator 40 is applied to a mode counter 41 which repetitively counts through 10. The output of the mode It counter 41 is applied to a BCD-decirnal decoder 42 which is enabled by output pulses from the square-wave oscillator. The outputs of the BCD-decimal decoder 42, which are labeled C2 through C10, are a series of 16 kilohertz clock pulses with the leading edge of one pulse delayed from the leading edge of the previous pulse by one cycle of the 160 kilohertz square-wave. The first pulse Cl is not used.

The C9 output pulse is applied to a clock gate 43 which is inhibited when a car wheel is sensed as will be explained hereinbelow. The output of the clock gate 43 is applied as a clock signal to a mode 10 counter 44 and to a mode to counter 45. The output of the mode 10 counter 44 is applied to a (1:10 decoder gate 46 which detects each count of 10 from the mode 10 counter 44 and a C10 clock pulse. The resulting output signal we C110 of the we decoder gate 46 is a 1.6 kilohertz signal. Similarly, the output of the mode 16 counter 45 is applied to a (p16 decoder gate 47 which detects each count of 16 from the mode 16 counter 45 and a C10 clock pulse. The resulting output signal 16-C10 of the (i116 decoder gate 47 is a 1.0 kilohertz signal.

The wheel sensor 24 produces an appropriately amplified and filtered signal WI-IL whenever awheel, or axle, is detected by a wheel detector located adjacent the track. (The width of the WI-IL pulse as illustrated in the timing diagram of FIG. 5 depends on the speed of the train.) The WHL signal enables a wheel synchronizer 48 so that upon the subsequent occurrence of the trailing edge of a C4 pulse the wheel synchronizer 48 is set to produce a WHL-C4-l0 output signal. The trailing edge of pulse C10 resets the wheel synchronizer 48 terminating the WI-IL-C4-l0 pulse. The wheel synchronizer 48 is not cleared until termination of the Wl-IL signal. Thus, the WI-IL-C4-10 pulse occurs only once for each wheel sensed.

The C5 through C8 pulses are applied to a wheel load control gate 49 which is enabled by a WI-IL-C4-l0 signal to produce output pulses WHL-CS through WHL-CS once for each wheel detected. These pulses are employed in other sections of the apparatus as will be explained hereinbelow.

The clock gate 43 is inhibited by the WI-IL-C4-l0 signal, and both the mode 10 counter 44 and the mode To counter 45 are reset by the WI-IL-C4-l0 signal so that they begin counting together after the WHL-C4-l0 pulse terminates.

Gap Detector The gap detector 31, as illustrated in detail in FIG. 6, employs information from the timing and wheel synchronizing circuitry 30 to determine when a truck has completely passed the detection point and to produce an output signal (B FULL) when the last wheel of the truck has moved a particular distance past the wheel detector. In the system as described herein the B FULL signal is produced when the last wheel of the truck has moved past the detection point a distance equal to 1.6 times the spacing between the next-to-last wheel and the last wheel of the truck. This particular relationship has been chosen because it has been found that the majority of carrier vehicles presently employed in piggyback operations by the American railroads have two trucks located so that the distance from the center of each outer wheel to the face of the adjacent coupler is 1.6 times the center-to-center distance between the last two wheels of the truck.

The gap detector 31 operates on a timing basis, measuring the time intervals between signals initiated by the wheel sensor 24. In order to provide correspondence between time measurements and -distance, a substantially constant rate of movement of a car past the wheel detector is assumed. The time interval between passage of two adjacent wheels of a truck past the wheel detector is measured in a counter A 50. Data representative of the time interval is loaded in counter B 51. Counter B 51 determines when a calculated period equal to 1.6 times the loaded time interval has transpired and then causes a B FULL signal to be produced. In the event another wheel is detected before termination of the calculated period, the counter B 51 is cleared, data representative of the newest time interval is transferred from counter A 50 to counter B 51, and counter B 51 initiates measuring of a new calculated period equal to 1.6 times the new time interval.

More specifically, when the first wheel of a truck is detected, counter A St) is loaded to all ls by a WI-IL- C8 signal. Since an A empty detector 52 then detects that counter A 50 is not empty, it does not produce a signal to inhibit a counter A clock gate 53. That is, the

'counter A clock gate 53 is enabled so that upon termination of a WHL-C4-10 signal from the timing and wheel synchronizing circuitry 30, 10-C 10 pulses from the (1)10 decoder gate 46 (FIG. 4) pass through the counter A clock gate 53 causing counter A 50 to count downward from the all ls condition at a rate of 1.6 kilohertz.

' Counter B 511 has the same number of stages as counter A 50; thus, both counters have the same maximum count value when loaded with all ls. Counter B 51 is controlled by a counter B control gate 54. When the counter B control gate 54 is in an initial reset 1 condition as established by a previous reset signal, either WCRS or RS, it produces an output signal which inhibits a counter B clock gate 55 and also passes through an OR gate 56 to hold counter B 51 cleared to all Os.

On the first wheel of a truck, the WI-IL-C4-lil signal enables the counter B control gate 54 and the WI-IL-C6 pulse changes it from-its reset 1 to a reset 2 condition. Under this condition the output signal inhibiting the counter B clock gate 55 and holding counter 18 511 cleared to all Os remains the same.

On detection of the next wheel, the WHL-C6 pulse together with the WI-IL-C4-10 enabling signal sets the counter B control gate 54 removing the output signal from the OR gate 56 and from the inhibiting input to the counter B clock gate 55. On the Wi-IL-C'7 pulse the accumulated count in counter A 50 is loaded into counter B 51. This count is a measure of the time interval between passage of the two wheels past the wheel detector; that is, the count is the number of 1.6

kilohertz pulses that have occurred during the time interval. The WHL-CS pulse again loads all ls into counter A 50.

Upon termination of the Wl-lL-C4-10 signal, the decoder gate 46 and 16 decoder gate 47 in the timing and wheel synchronizing circuitry 30 (FIG. 4) produce their respective pulse trains to counter A 50 and counter B 51 through the counter A clock gate 53 and counter B clock gate 55, respectively. Counter A 50 starts a new count downward from all l's at a rate of 1.6 kilohertz, and counter B 51 counts upward from the count transferred from counter A 50 at a rate of 1.0 kilohertz. Counter B 51 thus counts at a rate which is (1/1.6) that of counter A 50.

In the event that the wheel detector detects another wheel before the counter B 51 has counted upward to all ls, the WHL-C6 pulse clears counter B 51 to all Os. The count accumulated in counter A 50 is transferred to counter B 51 on the WHL-C7 pulse and counter A 50 is loaded to all ls on the Wl-lL-C8 pulse. The counter B control gate 54 is not affected since it is already in its set condition. Upon termination of the WHL-C4-10 signal, the procedure of counter A 50 counting downward from all ls on the (MO-C10 pulses and counter B 51 counting upward from the count transferred from the counter A on the 16-C10 pulses is repeated.

When counter B 51 reaches the count of all ls, a B FULL detector 57 detects this condition and produces a B FULL signal. This signal indicates that a period equal to 1.6 times the time interval between passage of the last two detected wheels has elapsed without detection of another wheel. Thus, it is assumed that the truck, whether it had two or three wheels, has completely passed the wheel detector.

The B FULL signal immediately inhibits the counter B clock gate 55, continuing the B FULL signal from the B FULL detector 57. The B FULL signal enables reset of the counter B control gate 54 to the reset 1 condition terminating the B FULL signal upon occurrence of a B FULL(SYNC) signal at an OR gate 58. As will be explained hereinbelow a B FULL (SYNC) signal is normally produced in the profile detector 32 after passage of the first truck of a car. The counter B control gate 54 is also reset to the reset 1 condition by WCRS or RS reset signals which occur after passage of the second truck of a car. As will also be explained hereinbelow, the counter B control gate 54 is reset to its reset 2 condition by a WC(-l) signal applied through an OR gate 60. When the counter B control gate 54 is in the reset 2 condition, only a single occurrence of the WHL-C4-10 enable-set signal and Wl-lL-C6 pulse are required to set the counter B control gate 54 and remove the output signal.

Profile Detector The profile detector 32, as shown in detail in FIG. 7, receives information on each wheel detected from the timing and wheel synchronizing circuitry 30 and on the passage of each truck from the gap detector 31. A wheel counter 65 counts upward on the wheels of the first truck of a car and downward on the wheels of the second truck. Various information on the accumulated wheel count and the detection of trucks is provided to other sections of the apparatus.

The wheel counter 65 is controlled by an up/down control gate 66. Under normal operating conditions the up/down control gate 66 is set by a previously occurring INT-LR reset signal to produce an UP output signal to an up clock gate 67. Thus, each WHL-CS pulse causes the wheel counter 65 to count in the upward direction from an initial count of zero. The accumulated count is read from the wheel counter 65 by the presence or absence of WC2 and WC2 signals.

When a B FULL signal is received from the gap detector 31 after an accumulated count of two or three wheels (a count of four is a special case which will be discussed hereinbelow), the up/down control gate 66 is enabled so that the trailing edge of the subsequent C2 pulse sets the up/down control gate 66 to produce a DOWN output signal and remove the UP output signal. In addition, during the C2 pulse, before the up/down gate 66 changes conditions, an end-of-first-truck detector 68 produces a pulse. Since normally a SYNC signal is present and a SYNC signal is not present, as will be explained hereinbelow, a middle-of-car detector 69 produces a B FULL (SYNC) pulse. This pulse, occurring during the C2 pulse subsequent to the start of the B FULL signal, is applied to the OR gate 58 of the gap detector 31 as explained previously and resets the counter B control gate 54 to the reset 1 condition. The B FULL signal is then terminated and the gap detector 31 is thus prepared for detecting the next truck.

With an accumulated count present in the wheel counter 65, A WCzb-WCd; detector 70 produces a signal at its WC output. This signal enables the down clock gate 71. Thus, since the up/down control gate 66 is producing a DOWN output signal, the succeeding Wl-lL-CS pulses pass through the down clock gate 71 causing the wheel counter 65 to count in the downward direction from the count accumulated during the previous counting upward. When the count in the wheel counter 65 reaches the initial count of zero, the WC- WC detector 70 produces a WC signal and no longer produces the WC signal. With the WC signal removed, the down clock gate 71 is no longer enabled. The occurrence of the WC signal indicates that, although a B FULL signal has not yet been produced, the second truck (assuming it has the same number of wheels as the first truck) has passed the wheel detector.

The profile detector 32 also includes a WC(-1) detector 72 preceded by a WC(-l) gate 73. These elements are employed to produce a WC(-l) signal if a wheel is detected after the wheel counter 65 has counted to zero but before a B FULL signal has been produced by the gap detector 31. This situation occurs when two cars are closely-coupled with their adjacent trucks set close to the adjacent ends of the cars such that the distance between the adjacent outer wheels is less than 1.6 times the distance between the last two wheels of the second truck of the first car. The WC(-l) gate 73 passes a WHL-CS signal only when the wheel counter 65 is at zero causing a WC signal to be producedby the WC-WC detector 70 and when the up/down control gate 66 is producing a DOWN signal. This signal sets the WC(-l) detector 72 so that the subsequent C7 pulse changes its condition to produce a WC(-1) signal. The WC(-l) detector 72 is quickly reset to its initial condition by the C8 pulse immediately following the C7 pulse.

Since the WC(-l) signal indicates the detection of the first wheel of the first truck of the next car, the apparatus must be properly reset to include this information. The WC(-1) signal is applied to the wheel counter 65 causing it to load a wheel count of one (WCl). The WC(-1) signal is also applied to the counter B control gate 54 of the gap detector 31 (FIG. 6) by way of OR gate 60 to reset the counter B control gate 54 to the reset 2 condition.

The profile detector 32 also includes a WC4 detector gate 74 which produces a WC4 signal when a wheel count of three is present in the wheel counter 65 and a WHL-CS pulse is passed by the up clock gate 67. The occurrence of a WC4 signal indicates that a truck having four wheels per side has passed the wheel detector. This situation and the manner of employing the WC4 signal will be explained hereinbelow.

A gap-sync detector 75 produces a B FULL(SYNC) signal, coinciding with a C2 pulse, when a signal is passed by the end-of-first-truck detector 68 during the presence of a SYNC signal. The SYNC signal, which also sets the up/down control gate 66 to produce an UP signal, is generated in the profile synchronizer 34 (FIG. 9) when a situation requiring resynchronizing of the apparatus has been detected.

EOC/Reset Circuitry The EOC/reset circuitry 33, as shown in detail in FIG. 8, employs signals received from the gap detector 31 and profile detector 32 together with information from the decoding logic circuitry 22 as to whether or not a railroad car label has been detected by the system to produce an appropriate end-of-car (EOC) signal for the decoding logic circuitry 22. The EOC/reset circuitry 33 includes an EOC selector gate 80 which is set upon receipt of a LABEL signal from the decoding logic circuitry 22 indicating that a car label has been detected to produce a DET LABEL signal. Upon subsequent receipt of a signal at its clock input, the EOC selector gate 30 is triggered to produce a LABEL-EOC signal. If a signal at the clock input is received when the EOC selector gate 80 has not been set by a LABEL signal, a NO LABEL-EOC signal is produced.

A signal may be produced at the clock input of the EOC selector gate 80 by various combinations of circumstances. When a WC signal from the profile detector 32 (FIG. 7) and a B FULL signal from the gap detector 31 (FIG. 6) are applied to a WCqb-gap EOC generator 81 a C3 clock pulse which passes through an EOC clock generator 82 produces an output pulse. This pulse passes through an OR gate 83 producing an EOC* signal and also passes through OR gates 84 and 85 to trigger the EOC selector gate 80. If a LABEL signal has previously been detected a LABEL-EOC signal is produced. If a LABEL signal has not been detected, a NO LABEL-EOC signal is produced.

The EOC selector gate 80 is also triggered to produce an appropriate EOC signal by a WC(-l) signal passing through OR gate 85 to the clock input of the selector gate 80.

A WC4 signal passes through OR gates 86, 84, and 85 to the clock input to trigger the EOC selector gate to produce an appropriate EOC signal.

Similarly, a B FULL(SYNC) signal which is produced as a result of an out-of-synchronism condition being detected, as will be explained hereinbelow,

.situation which will be discussed herein-below. The

output of the label-gap EOC generator 87 passes through OR gate 83 to produce an EOC* signal and through OR gates 84 and 85 to the clock input of the EOC selector gate 80 causing a LABEL-EOC or a NO LABEL-EOC signal to be produced.

The EOC clock generator 82 which normally passes C3 timing pulses to the WCda-gap EOC generator 81 and the label-gap EOC generator 87 is inhibited by the presence of a B FULL (SYNC) signal occurring during a re-synchronizing situation.

Various other gates included in the EOC/reset circuitry 33 and shown in FIG. 8, namely, a SYNC-RS gate 88, an INT-RS gate 89, and a WC(-1)-RS gate 90 produce appropriate resetting signals depending upon the particular sets of conditions present. The SYNC-RS gate 88 is set by a B FULL(SYNC) signal so that it is triggered on the succeeding C3 pulse to produce the SYNC-RS signal. The subsequent C4 pulse resets the SYNC-RS gate 88 to its original condition.

The INT-RS gate 89 is set by an output signal from the OR gate 84 which occurs during a WC4 signal, a B FULL(SYNC) signal, or an EOC* signal. The succeeding C6 clock pulse triggers the INT-RS gate 89 to produce an output signal which passes through an OR gate 9-! to produce the RS reset signal and also through an OR gate 92 to produce the INT-LR reset signal. The

INTRS gate 89 is reset to its original condition by the subsequent C7 clock pulse.

The occurrence of the WC(-1) signal sets the WC(- l)-RS gate 90 so that the subsequent C9 clock pulse triggers the gate producing an INT-LR reset signal at the output of the OR gate 92. The WC(-ll)-RS gate 90 is reset to its original condition by the subsequent Cllll pulse.

Both RS and INT-LR reset signals are also produced at the outputs of OR gates 91 and 92, respectively, by an LR reset signal from the decoding logic circuitry 22. Profile Synchronizer The profile synchronizer 34, as shown in detail in FIG. 9, receives signals from the profile detector 32, the EOC/reset circuitry 33 and from the decoder logic circuitry 22 and determines whether or not the apparatus is operating in synchronism with the cars of the train. If the apparatus is not properly synchronized, corrective signals are generated and applied to other sections of the apparatus.

Normally, a master SYNC gate 95 is in a reset condition producing a SYNC signal to the middle-of-car detector 69 of the profile detector 32 (FIG. 7). This situation remains constant during normal operation of the apparatus while the signals received by detecting wheels and by reading car labels indicate proper synchronism of the apparatus with the railroad train passing the scanning unit. The master SYNC gate 95 is switched to a condition to produce a SYNC output signal in place of the SYNC signal by the detection of certain out-of-synchronism conditions.

A label-parity detector 96 produces an output signal when signals are received from the decoding logic circuitry 22 indicating that a car label has been detected and the data read from the label passes the parity check. If a signal is produced by the label-parity detector 96 while a WC-SYNC gate 97 is enabled by a WCqb signal, the master SYNC gate 95 is set to the condition to produce the SYNC output signal. In addition, the WCRS output signal of the WC-SYNC gate 97 resets the counter B control gate 54 of the gap detector 31 to the reset 1 condition.

An EOC* signal sets an EOC-SYNC gate 98 so that the occurrence of a signal from the label-parity detector 96, before the occurrence of a WHL-CS signal to reset the EOC-SYNC gate 98 to its original condition, causes an output signal which switches the master SYNC gate 95 to produce the SYNC output signal. The EOC-SYNC gate 98 is then reset to its original condition by the next WI-IL-CS pulse.

A SYNC 1 output signal is produced by a SYNC l gate 99 when the gate is switched by a WHL-C pulse occurring during the presence of a DET LABEL signal. The SYNC F 1 signal is applied to the label-gap EOC generator 87 in the EOC/reset circuitry 33. Termination of the DET LABEL signal resets the SYNC 1 gate 99 to its original condition.

Summary of Operation Standard Cars The apparatus as described operates in the following manner during the passage of a railroad car of standard type past the wheel detector of the wheel sensor 24. It is assumed that as the car approaches the wheel detector the apparatus is in a fully reset condition, which may be insured by an LR reset signal from the decoding logic circuitry 22. The timing and wheel synchronizing circuitry 30 continuously produces the clock pulses C2 through C as shown in the timing diagram of FIG. 5.

When the first wheel of the first truck of a railroad car passes the wheel detector, the wheel sensor 24 produces a WI'IL signal. The timing and wheel synchronizing circuitry 30 produces the WHL-C4-l0 signal and the WHL-CS through WI-IL-C8 series of signals as shown in the timing diagram of FIG. 5, once for each WI-IL signal. The first wheel detected causes counter A 50 of the gap detector 31 (FIG. 6) to be loaded with all ls so as to begin counting downward on the dalO-CIO pulses from the 10 decoder gate 46 (FIG. 4) after termination of the WI-IL-C4-l0 signal. The counter B control gate 54 is changed from the reset 1 to the reset 2 condition, but its output signal continues to hold counter B 51 cleared to all 0s and to inhibit the counter B clock gate 55. The wheel counter 65 of the profile detector 32 stores a count of one.

Upon detection of a second wheel, the count accumulated in the counter A 50 which is a measure of the distance between the two wheels, is loaded into the counter B 51 which is prevented from clearing since the counter B control gate 54 has been switched to the set condition and there is no output signal therefrom. Thus, upon termination of the WI-IL-C4-10 signal, counter B 51 begins counting upward on the 16-Cl0 pulses and counter A 50, which has been re-loaded with all ls, begins counting downward on the rpm-C10 pulses. The wheel counter 65 of the profile detector 32 now stores a count of two.

Since counter B 51 counts upward at a rate which is (1/1 .6) the rate at which counter A 50 accumulated the count now loaded in counter B, if the truck has a third wheel, it will be sensed before counter B 51 counts upward to all ls. If a third wheel is detected, the counter B 51 is cleared to all Os, the newly accumulated count in counter A is transferred to counter B 51, and counter A 50 is again loaded with all ls. The count in the wheel counter 65 of the profile detector 32 is increased to three. Upon termination of the WHL-C4-l0 signal, counter A 50 counts downward on the 10-C10 pulses and counter B 51 counts upward on the 4116- C10 pulses.

When counter B 51 counts upward to all ls, regardless of whether this condition occurs after the second wheel of a two-axle truck or the third wheel of a three-axle truck, a B FULL signal is produced. This situation indicates that the last wheel of the truck has moved past the detection point a distance equal to 1.6

times the spacing between the next-to-last and last wheels, and therefore, the first truck has completely passed the detection point.

During the C2 pulse following the start of the B FULL signal the middle-of-car detector 69 produces a B FULL(SYNC) pulse which is applied to the counter B control gate 54. On the trailing edge of the C2 pulse, the up/down control gate 66 (FIG. 7) is set to produce the DOWN signa@ce the count in the wheel counter 65 is not zero, a WC signal is produced by the WC- WC detector 70 enabling the down clock gate 71. In addition, on the trailing edge of the C2 pulse the coinciding trailing edge of the B FULL(SYNC)pulse causes the counter B control gate 54 to be reset to the reset 1 condition.

Thus, after passage of the first truck completely past the wheel detector the wheel counter 65 has an accumulated count of two or three stored therein, depending on the number of wheels per side on the truck, the up/down control gate 66 and down clock gate 71 are in condition to cause the wheel counter 65 to count downward, and the gap detector 31 is in its original condition in readiness to detect passage of the next truck.

During passage of the wheels of the second truck past the wheel detector, the gap detector 31 operates in a similar manner to produce a B FULL signal when a gap greater than l.6 times the spacing between adjacent wheels is detected. The wheel counter 65 in the profile detector 32 (FIG. 7) counts downward on each wheel detected, and reaches a count of zero before the B FULL signal is generated by the gap detector 31.

With a count of zero in the wheel counter 65, the WCWC detector 70 produces a WC output signal in place of the WC signal. The B FULL signal and the WC signal are applied to the WCda-gap EOC generator 81 in the EOC/reset circuitry 33 (FIG. 8), and on the subsequent C3 pulse an appropriate EOC signal, either a LABEL-EOC or a NO LABEL-EOC signal, is produced by the EOC selector gate 80. Appropriate RS and INT-LR resetting signals are generated to reset the apparatus in condition for detecting the following car.

The apparatus operates in the foregoing manner for monitoring the passage of standard two-truck railroad cars, both trucks having either two or three axles. If the trucks are positioned in the manner which is standard for the majority of flat cars carrying piggyback cargo, the endrof-car signal will occur approximately when the region of the coupler passes the detection point. If the trucks are set inward from the end of the car a distance greater than 1.6 times the distance between the wheels, the end-of-car signal will occur somewhat prior to the passage of the end of the car but after passage of the last wheel.

Closely-Coupled Cars If the cars are of a type which are closely-coupled with the trucks positioned close to the ends of the cars so that the first wheel of the following car is located closer to the last wheel of the preceding car than 1.6 times the distance between adjacent wheels, a different operating situation takes place. The first truck of the car may be detected as explained previously. However, while counter B 51 of the gap detector 31 is counting upward after the last wheel of the second truck is detected, the first wheel of the next truck is detected. When this action occurs, the wheel counter 65 has reached a count of zero indicating that the last wheel of the car has passed, and the up/down control gate 66 produces a DOWN signal. The WC signal from the WC-WC detector 70 and the DOWN signal enable the WC(-1) gate 70 so that the WHL-CS signal generated by the first wheel of the following car sets the WC(-l) detector 72 and the subsequent C7 pulse causes a WC(-l) output. The WC(-l) signal passes to the EOC selector gate 80, and the appropriate LABEL- EOC or NO LABEL-EOC signal is produced.

Since in the foregoing situation the first wheel of the first truck of the following car is being employed to initiate the EOC signal, after passage of that wheel, a full reset of the apparatus is not appropriate. Instead, the WC(-l) signal is applied to the wheel counter 65 and loads the wheel counter with a count of one. The WC(- 1) also reset the counter B control gate 54 of the gap detector 31 to the reset 2 condition indicating that the first wheel of a truck has been detected. In addition, the WC(-1)-RS gate 90 generates an INT-LR reset signal which resets the up/down control gate 66 to produce the UP signal.

Cars with Four-Axle Trucks In the event a railroad car having four-axle trucks passes the trackside unit, the apparatus operates in the following manner. The labeling requirements of the American railroads for railroad cars having four-axle trucks call for the car to be labeled twice, with identical labels affixed in the regions between the second and third wheels of each truck. The apparatus operates in the manner previously described with the wheel counter 65 counting upward to a count of three during passage of the first three wheels of the first truck. The WC4 detector gate 74 is thereby enabled so that when a fourth wheel is detected without an intervening B FULL signal being generated, the WHL-CS pulse causes a WC4 signal to be produced by the WC4 detector gate 74. The WC4 signal passes to the EOC selector gate 80, and an appropriate end-of-car signal is produced.

The apparatus is completely reset by an RS and INT- LR reset signal. The second truck of the car causes the apparatus to duplicate the procedure as described.

Thus, a carrier having two four-axle trucks is processed twice, providing two separate end-of-car signals, on each of the fourth wheel of each truck.

Out-of-Synchronization Situations The apparatus operates so as to re-synchronize when an out-of-synchronism condition exists between the apparatus and the cars being monitored. One such situation occurs when a label has been detected and a B FULL signal has been generated by the gap detector 31 but the wheel counter 65 has not reached a wheel count of zero. The WI-lL-CS pulse generated by the next wheel causes the SYNC 5 l gate 99 to produce a SYNC 1 signal. The SYNC 1 signal, the WC signal from the WC-WC detector 70, and the B FULL signal, together with the C3 pulse causes the label-gap EOC generator 87 to produce a signal to the EOC selector gate 80 thereby generating a LABEL- EOC signal and a full reset of the apparatus: This combination of conditions may occur, for example, when in the process of counting downward, a wheel on the second truck is missed. The apparatus also operates in the foregoing manner in detecting a car having a first truck with three axles and a second truck with two axles.

Re-synchronizing is called for when an end-of-car signal has been generated by way of the WCdrgap EOC generator 81 or the label-gap EOC generator 87 and then LABEL and PARITY signals are received from the decoding logic circuitry 22. This combination of conditions implies that a car label is located in the region of the end of the car, a situation which is not consistent with standard labeling practice. The presence of the LABEL, PARITY and E00 signals causes the EOC-SYNC gate 98 to set the master SYNC gate 95 to produce the SYNC signal in place of the SYNC signal.

The SYNC signal sets the up/down control gate 66 of the profile detector 32 to produce the UP signal. Since under these conditions there is a B FULL signal, the subsequent C2 signal passes through the end-of-firsttruck detector 68 causing the gap-SYNC detector to produce a B FULL(SYNC) pulse. This pulse causes the SYNC-RS gate 88 to produce a SYNC-RS signal which resets the master SYNC gate 95. The apparatus is otherwise reset to accept the next detected wheel as the first wheel of the first truck of a car by the RS and INT- LR reset signals produced by the EOC* signal.

Another combination of conditions indicating the necessity for re-synchronizing the apparatus is a wheel count of zero and the receipt of LABEL and PARITY signals. This combination implies that a car label is located outward of the last wheel of the car, a situation which is not consistent with standard labeling practice. The LABEL and PARITY signals cause a signal from the label-parity detector 96 which together with the W011 signal causes the WCd -SYNC gate 97 to set the master SYNC gate to produce the SYNC signal. The SYNC signal sets the up/down control gate 66 to produce the UP signal. In addition, the WCRS signal from the WCdr-SYNC gate 97 sets the counter B control gate 54 to the reset 1 condition. Thus, the apparatus is in condition to consider the next truck as the first truck of a car. After the next truck passes the detection point and a B FULL signal is produced, the gap- SYNC detector 75 produces a B FULL(SYNC) pulse.

The B FULL(SYNC) pulse causes the SYNC-RS gate 88 to produce a SYNC-RS pulse resetting the master SYNC gate 95 to produce the SYNC signal in place of the SYNC signal. Thus, the apparatus is fully resynchronized and in its normal operating condition to detect the second truck of a car.

Conclusion The apparatus as shown and described, when employed in monitoring the passage of carrier vehicles of the type most commonly used in piggyback operations, produces an end-of-car signal when the region of a coupler passes the detection point. For other types of cars, such as closely-coupled cars with the trucks mounted very close to the ends of the cars or cars having fouraxle trucks, appropriate end-of-car signals are produced which correspond reasonably well with passage of the cars past the detection point.

Thus, since a more accurate determination of the passage of the ends of cars is possible employing the disclosed apparatus, the requirements for placing labeled trailers or containers on carrier vehicles in piggyback arrangement may be less stringent, that is, trailers or containers may be placed on the carrier vehicles with their labels outward of the outer wheels. Heretofore it has been necessary that trailers or containers be placed with their labels inward of the outer wheels in order for the label reading system to properly associate the trailers or containers with their carrier vehicles. The apparatus as described also provides for re-synchronizing under conditions wherein a detected car label incorrectly appears to be located on a car in an improper position relative to the detected profile of the car.

While there has been shown and described what is consi-dered a preferred embodiment of the present invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.

What is claimed is:

1. Apparatus for monitoring the movement of groups of objects along a predetermined path including sensing means for sensing the passage of an object past a point on the path of movement of the objects;

first timing means coupled to the sensing means and operable to measure the time interval between passage of adjacent objects of a group past said point;

storage means coupled to the first timing means and operable to store data representing the measured time interval;

second timing means associated with the storage means and operable to measure a calculated period of time bearing a predetermined relationship to the time interval stored in the storage means;

indicating means coupled to the second timing means and operable to provide an indication at the termination of the calculated period of time; and means coupled to the sensing means and to the second timing means and operable in response to sensing of another object prior to termination of said calculated period of time to cause the second timing means to initiate measuring a new calculated period of time bearing said predetermined relationship to the new time interval measured by the first timing means and stored in the storage means in response to sensing of said other object.

2. Apparatus for monitoring the movement of pairs of groups of objects along a predetermined path includmg sensing means for sensing the passage of an object past a point on the path of movement of the objects;

first timing means coupled to the sensing means and operable to measure the time interval between passage of adjacent objects of a group past said point;

storage means coupled to the first timing means and operable to store data representing the measured time interval; second timing means associated with the storage means and operable to measure a calculated period of time bearing a predetermined relationship to the time interval stored in the storage means; indicating means coupled to the second timing means and operable to provide an indication at the termination of the calculated period of time;

output means coupled to the indicating means and operable to produce an output signal in response to an indication from said indicating means after passage of the second pair of groups of objects past said point subsequent to an indication from said indicating means of the passage of the first of a pair of groups of objects past said point;

means coupled to the sensing means and to the second timing means and operable in response to sensing of another object prior to termination of said calculated period of time to cause the second timingmeans to initiate measuring a new calculated period of time bearing said predetermined relationship to the new time interval measured by the first timing means and stored in the storage means in response to sensing of said other object; and

object counting means coupled to the sensing means and to the output means and operable to count the number of objects of each group of objects sensed between said indications and to permit the output means to produce an output signal in response to the indication after passage of said second pair of objects only when the number of objects of the second pair is equal to the number of objects of the first pair.

3. Apparatus for monitoring the movement of railroad cars long railroad tracks, each railroad car having a pair of trucks with a plurality of axles, said apparatus including sensing means for sensing the passage of an axle of a truck past a point on the tracks;

first timing means coupled to the sensing means for measuring the time interval between passage of adjacent axles of a truck past said point;

second timing means coupled to the sensing means and to the first timing means for providing an indication a calculated period of time after passage of the last axle of a truck past said point, said calculated period of time bearing a predetermined relationship to the time interval between passage of the nextdto-last and last axles of the truck past said point;

output means coupled to the second timing means 5. Apparatus for monitoring the movement of railroad cars along railroad tracks, each railroad car having a pair of trucks with a plurality of axles, said apparatus including for producing an output signal in response to an in- 5 sensing means for sensing the passage of an axle past dication from said ,second timing means after a Point thfi tracks; passage of the second of a pair of trucks past said a first Source of Pulses for Producing Pulsfis at a first point subsequent to an indication from said second frequency timing means of the passage of the first of the pair I 0 a Second Source of Pulses for'pmducing Pulses at a of trucks past said point; closely-coupled car detection means coupled to the sensing means for producing a signal in response to the passage of another axle past said point after passage of the last axle of the second of a pair of trucks past said point and before an indication from said second timing means a calculated period of time after passage of the last axle of the second truck past said point; and

and to the first timing means for providing an indication a calculated period of time after passage of the last axle of a truck past said point, said calculated period of time bearing a predetermined relationship to the time interval between passage of the next-to-last and last axles of the truck past said point;

I output means coupled to the second timing means for producing an output signal in response to an indication from said second timing means after 45 l: t fi for countmg F f 9 passage of the second of a pair of trucks past said P e to 6 s: f f to point subsequent to an indication from said second 3 T t: sinsmg means timing means of the passage of the first of the pair 6 O i e tans i or accumu a count m said second counting means after a signal of trucks past said point, 50 f label means for receiving a signal indicating the Sald q f means mm] the passage of two ax es past sat point. i i of :2 on a 21 F and f 8. Apparatus in accordance with claim 7 wherein pro Slgna response said first counting means is operable to be loaded to synchronizing means coupled to said label means for maximum count value i nse to passage of an providing a signal in response to the presence of a 55 second frequency;

first counting means coupled to the sensing means and to the first source of pulses and operable to accumulate a count of the number of pulses from the first source occurring during the time interval between passage of two adjacent axles past said point;

second counting means coupled to the sensing means, the second source of pulses, and the first counting means;

means coupfiPg said closely'coupledcar i loading means coupled to the sensing means and to means to said output means for causing said output the second counting means and operable to means to Produce an output slgnal m response to a transfer the count accumulated in the first countsignal from said closely-coupled car detection ing means to the Second counting means in means 25 response to passage of the second of two adjacent v 4. Apparatus for monitoring the movement of railaxles past said point;

road cars long railroad tracks, each railroad car having said second counting means being operable a P of trucks with a plurality of axles Said apparatus sequent to transfer of a count from the first countincluding I ing means to count pulses from the second source;

sensing means for sensing the passage of an axle of a and truck pastapoint on the tracks; indicating means coupled to the second counting first timing means coupled to the sensing means for means and operable to provide a signal when the measuring the time interval between passage of adcount of the number of pulses from the second jacent axles of a truck past said point; source equals the count transferred from the first second timing means coupled to the sensing means counting means.

6. Apparatus in accordance with claim 5 including clearing means coupled to the sensing means and to the second counting means and operable to remove from the second counting means the effects of the count transferred from the first counting means and the count of the number of pulses from the second source in response to passage of an axle past said point.

7. Apparatus in accordance with claim 6 including axle past said point, and is operable to count downward on pulses applied thereto from said first source of pulses;

said second counting means has a maximum count value equal to the maximum count value of the first counting means, and is operable to count upward on pulses applied thereto from said second source of pulses;

said second frequency is less than said first frequency; and

said indicating means is operable to produce said signal when the count in the second counting means equals said maximum count value.

9. Apparatus for monitoring the movement of railroad cars along railroad tracks, each railroad car having a pair of trucks with a plurality of axles, said apparatus including sensing means for sensing the passage of an axle past a point on the tracks; a first source of pulses for producing pulses at a first frequency, a second source of pulses for producing pulses at a second frequency; first counting means coupled to the sensing means and to the first source of pulses and operable to accumulate a count of the number of pulses from the first source occurring during the time interval between passage of two adjacent axles past said point; second counting means coupled to the sensing means, the second source of pulses, and the first counting means; loading means coupled to the sensing means and to the second counting means and operable to transfer the count accumulated in the first counting means to the second counting means in response to passage of the second of two adjacent axles past said point; said second counting means being operable subsequent to transfer of a count from the first counting means to count pulses from the second source; indicating means coupled to the second counting means and operable to provide a signal when the count of the number of pulses from the second source equals the count transferred from the first counting means; axle counting means coupled to said sensing means for counting the passage of axles past said point; and control means for said axle counting means coupled to the axle counting means and to said indicating means and operable to cause the axle counting means to count in one direction when in a first condition and operable to cause the axle counting means to count in the opposite direction when in a second condition, said control means being normally set in the first condition and being set to the second condition in response to a signal from said indicating means, whereby theaxle counting means counts in the one direction from an initial value as each axle passes said point and subsequent to a signal from the indicating means counts in the opposite direction toward the initial value as each axle passes said point; said axle counting means being operable to produce a signal when the count in the axle counting means is at said initial value. 10. Apparatus in accordance with claim 9 further including output means coupled to said indicating means and to said axle counting means and operable to produce an output signal in response' to concurrent signals from said indicating means and from said axle counting means. 11. Apparatus in accordance with claim 10 wherein said second frequency is less than said first frequen- Y; and including clearing means coupled to the sensing means and to the second counting means and operable to remove from the second counting means the effects of the count transferred from the first counting means and the count of the number of pulses from the second source in response to passage of an axle past said point; and

control means for said second counting means coupled to the second counting means, to said indicating means, and to said sensing means, and operable to prevent the transfer or accumulation of a count in said second counting means after a signal from said indicating means until the passage of two axles past said point.

12. Apparatus in accordance with claim 11 including closely-coupled car detection means coupled to the sensing means, to the control means for the axle counting means, and to the axle counting means, and operable to produce a closely-coupled car signal in response to passage of an axle past said point while the control means for the axle counting means is in the second condition and said signal is being produced by the axle counting means; and

means coupling said closely-coupled car detection means to said output means and operable to cause said output means to produce an output signal in response to a closely-coupled car signal from said closely-coupled car detection means.

13. Apparatus in accordance with claim 12 including means coupling the closely-coupled car detection means to said axle counting means and operable to set the axle counting means at a count of one axle in the one direction from the initial value in response to closely-coupled car signal;

means coupling the closely-coupled car detection means to the control means for the axle counting means and operable to set the control means for the axle counting means in the first condition in response to a closely-coupled car signal; and

means coupling the closely-coupled car detection means to the control means for the second counting means and operable to cause the control means for the second counting means to prevent an accumulation of a count in the second counting means until the subsequent passage of one axle past said point.

14. Apparatus in accordance with claim 11 including label signal means for receiving a signal indicating the presence of a readable label mounted on a railroad car and operable to produce a label signal in response to receiving said signal;

synchronizing means coupled to the sensing means, to the indicating means, to the axle counting means, and to the label signal means, and operable to produce synchronizing signal in response to a label signal occurring after the occurrence of signals from the indicating means and the axle counting means and before the passage of another axle past said point;

means coupling the synchronizing means to the control means for the axle counting means and operable to set said control means for the axle counting means to the first condition in response to a synchronizing signal;

15. Apparatus in accordance with claim 11 including label signal means for receiving a signal indicating the presence of a readable label mounted on a railroad car and operable to produce a label signal in response to receiving said signal;

synchronizing means coupled to the axle counting means and to the label signal means and operable to produce a synchronzing signal in response to a label signal occurring during the occurrence of a signal from the axle counting means;

means coupling the synchronizing means to the control means for the axle counting means and operable to set said control means for the axle counting means to the first condition in response to a synchronizing signal;

means coupling the synchronizing means to the control means for the second counting means and operable to prevent the transfer or accumulation of a count in said second counting means after occurrence of a synchronizing signal until the passage of two axles past said point;

means coupled to the indicating means, to the synchronizing means, and to the output means, and operable to cause said output means to produce an output signal in response to the next signal from said indicating means after initiation of a synchronizing signal; and

means coupled to the indicating means and to the synchronizing means and operable to cause the synchronizing means to maintain the synchronizing signal until after the occurrence of said next signal from said indicating means. 

1. Apparatus for monitoring the movement of groups of objects along a predetermined path including sensing means for sensing the passage of an object past a point on the path of movement of tHe objects; first timing means coupled to the sensing means and operable to measure the time interval between passage of adjacent objects of a group past said point; storage means coupled to the first timing means and operable to store data representing the measured time interval; second timing means associated with the storage means and operable to measure a calculated period of time bearing a predetermined relationship to the time interval stored in the storage means; indicating means coupled to the second timing means and operable to provide an indication at the termination of the calculated period of time; and means coupled to the sensing means and to the second timing means and operable in response to sensing of another object prior to termination of said calculated period of time to cause the second timing means to initiate measuring a new calculated period of time bearing said predetermined relationship to the new time interval measured by the first timing means and stored in the storage means in response to sensing of said other object.
 2. Apparatus for monitoring the movement of pairs of groups of objects along a predetermined path including sensing means for sensing the passage of an object past a point on the path of movement of the objects; first timing means coupled to the sensing means and operable to measure the time interval between passage of adjacent objects of a group past said point; storage means coupled to the first timing means and operable to store data representing the measured time interval; second timing means associated with the storage means and operable to measure a calculated period of time bearing a predetermined relationship to the time interval stored in the storage means; indicating means coupled to the second timing means and operable to provide an indication at the termination of the calculated period of time; output means coupled to the indicating means and operable to produce an output signal in response to an indication from said indicating means after passage of the second pair of groups of objects past said point subsequent to an indication from said indicating means of the passage of the first of a pair of groups of objects past said point; means coupled to the sensing means and to the second timing means and operable in response to sensing of another object prior to termination of said calculated period of time to cause the second timing means to initiate measuring a new calculated period of time bearing said predetermined relationship to the new time interval measured by the first timing means and stored in the storage means in response to sensing of said other object; and object counting means coupled to the sensing means and to the output means and operable to count the number of objects of each group of objects sensed between said indications and to permit the output means to produce an output signal in response to the indication after passage of said second pair of objects only when the number of objects of the second pair is equal to the number of objects of the first pair.
 3. Apparatus for monitoring the movement of railroad cars long railroad tracks, each railroad car having a pair of trucks with a plurality of axles, said apparatus including sensing means for sensing the passage of an axle of a truck past a point on the tracks; first timing means coupled to the sensing means for measuring the time interval between passage of adjacent axles of a truck past said point; second timing means coupled to the sensing means and to the first timing means for providing an indication a calculated period of time after passage of the last axle of a truck past said point, said calculated period of time bearing a predetermined relationship to the time interval between passage of the next-to-last and last axles of the truck past said point; output means coupled to the second timing means for producing an output signal in response to an indicatIon from said second timing means after passage of the second of a pair of trucks past said point subsequent to an indication from said second timing means of the passage of the first of the pair of trucks past said point; closely-coupled car detection means coupled to the sensing means for producing a signal in response to the passage of another axle past said point after passage of the last axle of the second of a pair of trucks past said point and before an indication from said second timing means a calculated period of time after passage of the last axle of the second truck past said point; and means coupling said closely-coupled car detection means to said output means for causing said output means to produce an output signal in response to a signal from said closely-coupled car detection means.
 4. Apparatus for monitoring the movement of railroad cars long railroad tracks, each railroad car having a pair of trucks with a plurality of axles, said apparatus including sensing means for sensing the passage of an axle of a truck past a point on the tracks; first timing means coupled to the sensing means for measuring the time interval between passage of adjacent axles of a truck past said point; second timing means coupled to the sensing means and to the first timing means for providing an indication a calculated period of time after passage of the last axle of a truck past said point, said calculated period of time bearing a predetermined relationship to the time interval between passage of the next-to-last and last axles of the truck past said point; output means coupled to the second timing means for producing an output signal in response to an indication from said second timing means after passage of the second of a pair of trucks past said point subsequent to an indication from said second timing means of the passage of the first of the pair of trucks past said point; label means for receiving a signal indicating the presence of a label on a railroad car and for producing a signal in response thereto; synchronizing means coupled to said label means for providing a signal in response to the presence of a signal from said label means after passage of the last axle of the second of a pair of trucks past said point and before the passage of another axle past said point; and means coupling the second timing means and the synchronizing means to said output means for causing the output means to produce an output signal subsequent to initiation of a signal from said synchronizing means in response to the next indication from said second timing means occurring after passage of the last axle of the next truck past said point.
 5. Apparatus for monitoring the movement of railroad cars along railroad tracks, each railroad car having a pair of trucks with a plurality of axles, said apparatus including sensing means for sensing the passage of an axle past a point on the tracks; a first source of pulses for producing pulses at a first frequency, a second source of pulses for producing pulses at a second frequency; first counting means coupled to the sensing means and to the first source of pulses and operable to accumulate a count of the number of pulses from the first source occurring during the time interval between passage of two adjacent axles past said point; second counting means coupled to the sensing means, the second source of pulses, and the first counting means; loading means coupled to the sensing means and to the second counting means and operable to transfer the count accumulated in the first counting means to the second counting means in response to passage of the second of two adjacent axles past said point; said second counting means being operable subsequent to transfer of a count from the first counting means to count pulses from the second source; and indicating means coupled to the second counting means and operable to provide a signal when the count of the number of Pulses from the second source equals the count transferred from the first counting means.
 6. Apparatus in accordance with claim 5 including clearing means coupled to the sensing means and to the second counting means and operable to remove from the second counting means the effects of the count transferred from the first counting means and the count of the number of pulses from the second source in response to passage of an axle past said point.
 7. Apparatus in accordance with claim 6 including control means for said second counting means coupled to the second counting means, to said indicating means, and to said sensing means, and operable to prevent the transfer or accumulation of a count in said second counting means after a signal from said indicating means until the passage of two axles past said point.
 8. Apparatus in accordance with claim 7 wherein said first counting means is operable to be loaded to maximum count value in response to passage of an axle past said point, and is operable to count downward on pulses applied thereto from said first source of pulses; said second counting means has a maximum count value equal to the maximum count value of the first counting means, and is operable to count upward on pulses applied thereto from said second source of pulses; said second frequency is less than said first frequency; and said indicating means is operable to produce said signal when the count in the second counting means equals said maximum count value.
 9. Apparatus for monitoring the movement of railroad cars along railroad tracks, each railroad car having a pair of trucks with a plurality of axles, said apparatus including sensing means for sensing the passage of an axle past a point on the tracks; a first source of pulses for producing pulses at a first frequency, a second source of pulses for producing pulses at a second frequency; first counting means coupled to the sensing means and to the first source of pulses and operable to accumulate a count of the number of pulses from the first source occurring during the time interval between passage of two adjacent axles past said point; second counting means coupled to the sensing means, the second source of pulses, and the first counting means; loading means coupled to the sensing means and to the second counting means and operable to transfer the count accumulated in the first counting means to the second counting means in response to passage of the second of two adjacent axles past said point; said second counting means being operable subsequent to transfer of a count from the first counting means to count pulses from the second source; indicating means coupled to the second counting means and operable to provide a signal when the count of the number of pulses from the second source equals the count transferred from the first counting means; axle counting means coupled to said sensing means for counting the passage of axles past said point; and control means for said axle counting means coupled to the axle counting means and to said indicating means and operable to cause the axle counting means to count in one direction when in a first condition and operable to cause the axle counting means to count in the opposite direction when in a second condition, said control means being normally set in the first condition and being set to the second condition in response to a signal from said indicating means, whereby the axle counting means counts in the one direction from an initial value as each axle passes said point and subsequent to a signal from the indicating means counts in the opposite direction toward the initial value as each axle passes said point; said axle counting means being operable to produce a signal when the count in the axle counting means is at said initial value.
 10. Apparatus in accordance with claim 9 further including output means coupled to said indicating means and to said axle counTing means and operable to produce an output signal in response to concurrent signals from said indicating means and from said axle counting means.
 11. Apparatus in accordance with claim 10 wherein said second frequency is less than said first frequency; and including clearing means coupled to the sensing means and to the second counting means and operable to remove from the second counting means the effects of the count transferred from the first counting means and the count of the number of pulses from the second source in response to passage of an axle past said point; and control means for said second counting means coupled to the second counting means, to said indicating means, and to said sensing means, and operable to prevent the transfer or accumulation of a count in said second counting means after a signal from said indicating means until the passage of two axles past said point.
 12. Apparatus in accordance with claim 11 including closely-coupled car detection means coupled to the sensing means, to the control means for the axle counting means, and to the axle counting means, and operable to produce a closely-coupled car signal in response to passage of an axle past said point while the control means for the axle counting means is in the second condition and said signal is being produced by the axle counting means; and means coupling said closely-coupled car detection means to said output means and operable to cause said output means to produce an output signal in response to a closely-coupled car signal from said closely-coupled car detection means.
 13. Apparatus in accordance with claim 12 including means coupling the closely-coupled car detection means to said axle counting means and operable to set the axle counting means at a count of one axle in the one direction from the initial value in response to closely-coupled car signal; means coupling the closely-coupled car detection means to the control means for the axle counting means and operable to set the control means for the axle counting means in the first condition in response to a closely-coupled car signal; and means coupling the closely-coupled car detection means to the control means for the second counting means and operable to cause the control means for the second counting means to prevent an accumulation of a count in the second counting means until the subsequent passage of one axle past said point.
 14. Apparatus in accordance with claim 11 including label signal means for receiving a signal indicating the presence of a readable label mounted on a railroad car and operable to produce a label signal in response to receiving said signal; synchronizing means coupled to the sensing means, to the indicating means, to the axle counting means, and to the label signal means, and operable to produce synchronizing signal in response to a label signal occurring after the occurrence of signals from the indicating means and the axle counting means and before the passage of another axle past said point; means coupling the synchronizing means to the control means for the axle counting means and operable to set said control means for the axle counting means to the first condition in response to a synchronizing signal; means coupled to the indicating means, to the synchronizing means, and to the output means, and operable to cause said output means to produce an output signal in response to the next signal from said indicating means occurring after initiation of a synchronizing signal; and means coupled to the indicating means and to the synchronizing means and operable to cause the synchronizing means to maintain the synchronizing signal until after the occurrence of said next signal from said indicating means.
 15. Apparatus in accordance with claim 11 including label signal means for receiving a signal indicating the presence of a readable label mounted on a railroad car and operable to produce a label signal in respoNse to receiving said signal; synchronizing means coupled to the axle counting means and to the label signal means and operable to produce a synchronzing signal in response to a label signal occurring during the occurrence of a signal from the axle counting means; means coupling the synchronizing means to the control means for the axle counting means and operable to set said control means for the axle counting means to the first condition in response to a synchronizing signal; means coupling the synchronizing means to the control means for the second counting means and operable to prevent the transfer or accumulation of a count in said second counting means after occurrence of a synchronizing signal until the passage of two axles past said point; means coupled to the indicating means, to the synchronizing means, and to the output means, and operable to cause said output means to produce an output signal in response to the next signal from said indicating means after initiation of a synchronizing signal; and means coupled to the indicating means and to the synchronizing means and operable to cause the synchronizing means to maintain the synchronizing signal until after the occurrence of said next signal from said indicating means. 